Question

1. Airline Water Quality

Is the water on your airline flight safe to drink? It isn’t feasible to analyze the water on every flight, so sampling is necessary. In August and September 2004, the Environmental Protection Agency (EPA) found bacterial contamination in water samples from the lavatories and gallery water taps on 20 of 158 randomly selected U.S. flights. Alarmed by the data, the EPA ordered sanitation improvements and then tested the water samples again in November and December of that year. In the second sample, bacterial contamination was found in 29 of 169 randomly sampled flights.   

1. Construct a 95 percent confidence interval for each period’s survey.   

Answer 1

ofano bazooo Sept 2004 DES Given n = 158 , a= 20 (sept-2004) * = = 20 = 0.1266 The 9st confidence idenal for P is & # Zap (1-B , where 29, 196, is the sepoticesty of z trzos (1- = 0.1266 +1.96 0.1266 (-0.1266 158 = 0 1266+ 0.0519 =(0-0747, 0.1785) The popushions of baderia coohai caloo betwee 0.0 747 cand o 1785 * Criver n=169 , x=29 Nov 2004) > Þ= -29 - 0.1716 The 95% confidence interval for Pis - Splint , where a = 1.96. : + z Flip- 0.171629/0106(1-01To = 0.1716 + 0.05 68 = (o. 1148 0.2284) u The proportion of bacterial Costaninations in Nov.rary lies betwees 6. 1148 and 0.2284 69 161